Smart Distribution Network.pdf

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2011The International Conference on Advanced Power System Automation and Protection

APAP2011 www.apap2011.org

*Corresponding author (email: [email protected])

Research on technical framework of smart distribution networkLI JianFang, MENG XiaoLi, SONG XiaoHui

China Electric Power Research Institute, Beijing 100192, China

Abstract: The future development trend of electric power grid is smart grid, which include such features as flexible, clean, se-

cure, economic, and friendly and so on. Smart grid involves power generation, transmission, transformation, distribution, con-

sumption and dispatching. Distribution network locates at the end of power system, and due to its direct connection with con-

sumers, the quality and ability of power supply is guaranteed by it. In this paper, the connotation, characteristics and the de-

velopment goals of smart distribution network in China are expounded firstly. Secondlythe technical framework of smart

distribution network, which include network infrastructure, information communication system and intelligent application sys-

tem, is put forward. The main technical compositions of the framework are briefly discussed in succession. Lastly, the sugges-tion on development path of smart distribution network in china is proposed, in the hope of providing reference to the further

research and implementation of smart distribution network.

Keywords: smart distribution network, technical framework, information and communication system, intelligent ap-

plication, development path

1 Introduction

With the increasing global pressure on resource and envi-

ronment, social improving the requirement for environment

protection, energy conservation and emission reduction,

sustainable development day by day. Meanwhile, theprocess of power market is promoting and the requirement

of the consumers for power supply reliability and power

quality is increasing, the power industry is facing unprece-

dented challenges. To provide more safe, reliable, clean and

efficient power supply become the common goal of the

power industry. In the future, the power grid will produce

more data and information, support bidirectional flow of

load and information, adapt to the access of various kinds of

distributed energy resource, meet the demands of consumers,

and the efficiency and social economic benefits of grid as-

sets is improved significantly. The United States and some

European Union countries put forward the concept of smart

grid, and consider it the future development trend of electric

power grid [1-4].

Due to the different development environment and driving

factors, there are differences in development path and empha-

sis among different countries. Based upon national conditions,

every country gives its own definition of smart grid. The core

of the smart grid is to conserve energy, reduce emission, im-

prove efficiency and reliability. Smart grid has become a vi-

sion for power industry all over the world, and it will promote

changes and improvements of the power industry.

Smart grid involves power generation, transmission, trans-

formation, distribution, consumption and dispatching [5-6].

Distribution network locates at the end of power system, and

due to its direct connection with consumers, the quality and

ability of power supply is guaranteed by it. Therefore, the

construction of smart distribution network plays an important

role of the smart grid.

2 The connotation and characteristics of smart

distribution network

2.1 The connotation of smart distribution network

Compared with distribution automation (DA), smart distri-

bution network covers all the content of distribution auto-

mation and even more, it nearly covers all the technology in

primary side and secondary side. Smart distribution network

is enhanced in performance, adapt to the access of

large-scale distributed energy resource and interacting with

consumers.

Smart distribution network covers a wide range, and thereis no generally accepted definition of smart distribution net-

work so far.

The core components, necessary systems and equipments

in smart distribution network are introduced in paper[7]. The

goal of the smart distribution network is to extend equipment

life, determine the priority of grid asset replacement, reduce

the cost of network reconstruction and avoid fault in advance

and so on [8]. It is noted that the smart distribution network is

the extension of advanced distribution automation (ADA), and

the main differences between traditional distribution network

and smart distribution network are: adapt to the access of var-

ious kinds of distributed energy resource and micro-grid oper-ation, encourage interaction with consumers [9].

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978-1-4244-9621-1/11/$26.00 2011 IEEE


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At present, many countries have formed a consensus during

the construction of smart distribution network based upon

national conditions. The connotation of smart distribution

network can be summarized as such aspects: based on physi-

cal entity grid, includes various kinds of distribution facilities

such as switches, distribution terminals, sensors; integrates avariety of modern advanced technology such as sensor mea-

surement, automation technology, communication technology,

information technology, control technology; adapt to the

access of various forms of distributed energy resource, energy

storage device and electric vehicle. Compared with traditional

distribution network, smart distribution network is more flexi-

ble and adjustable, significantly improves the security, relia-

bility, quality of power supply and the social economic bene-

fits of energy resource.

2.2 The characteristics of smart distribution network

Smart distribution network performances well in power

supply security, power quality and efficiency of grid assets.The characteristics of smart distribution network can be

summarized as: informationization, automation and interac-

tion(abbreviated as Three-tions).

Informationization is the basis for the realization of smart

distribution network. Informationization means the ability of

highly integrated, multi-share, deeply excavation of the

real-time and non real-time information, and it can be classi-

fied into two categories: the informationization of power pro-

duction and control, the informationization of power man-

agement.

Automation is the visual representation of the development

level of the smart distribution network, not limited to distribu-tion automation, but include optimization of network control

strategy, monitor of operation and fault restoration.

Interaction is the inherent requirement of smart distribution

network. Interaction has two meanings: firstly, adapt to the

access of various forms of distributed energy resource; se-

condly, interact with consumers, consumers can choose the

time of power consumption based on real-time price and have

own distributed energy resource interacted with the power

system[10-14].

2.3 The development goals of smart distribution network in

ChinaGeneration, transmission, transformation, distribution, con-

sumption and dispatching are the six application areas of

strong smart grid. The development goals of the smart dis-

tribution network in China are: a strong frame structure with

the characteristics of efficient and flexible, have a good

performance in reconfiguration, power flow optimization

and acceptance of distributed energy, compatibility and uni-

fied control of the distributed energy resource and energy

storage device, high reliability and quality of power supply.

3 The technical framework of smart distribu-

tion network

The construction of smart distribution network in China

needs to start with the basic areas and make the technical

framework in line with the development in China clear.

Smart distribution network, which combine modern ad-

vanced technology with traditional distribution technology and

focus on the improving of the overall performance and saving

of the overall cost, makes revolutionary changes in network

structure, relay protection and operation control mode and so

on.

The technical framework, which covers planning, construc-

tion, operation and management of the distribution network,

can be divided into physical entity layer, data layer and appli-

cation layer logically. The framework includes network infra-

structure, information communication system and intelligent

application system, just as figure 1 show.


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Figure 1 The technical framework of smart distribution network.

As the physical basis of the smart distribution network, the

physical entity layer locates at the bottom of the framework;

the data layer is the tremendous database of smart distribu-

tion network and it can provide data for the application

layer; the intelligence of distribution network is well embo-

died in the application layer.

3.1 Strengthen the network infrastructure

A strong and flexible network and intelligent distribution

equipments of safety and reliability are the basis of smart

distribution network.

(1) Strong and flexible network. Strong network is the pri-

mary goal of the smart distribution network construction in

China. Grid-connection of various kinds of distributed energy

has a great impact on network planning. The ability againstnatural disasters and other emergencies is necessary in future.

Innovation in planning process, planning modeling and plan-

ning method is indispensable.

(2)Intelligent distribution equipments. Intelligent distribu-

tion equipments include monitoring devices, protection devic-

es, control devices in secondary side and static compensators,

solid-state switches, distributed generation and energy storage

devices in primary side.

3.2 Construction of information and communication system

It is necessary to acquire various kinds of meter data, which

with the characteristics such as large amount, plenty of the

information points, higher requirement of real-time. The

requirements above-mentioned cant be satisfied in tradi-

tional information communication system, therefore ad-

vanced sensing technology, unified information model and

open communication platform should be enhanced.

(1)Advanced sensing technology. Based on sensing tech-

nology, power system planners and operators can acquire a lot

of data such as load, voltage, current, power factor, phase rela-

tion, temperature, and monitor the healthy state of equipment,

recognize the operation condition, evaluate the security and

stability of power system.

(2)Open communication platform. Existing communication

system, which based on the one-way flow of information,

cant meet the requirement of bi-direction flow in smart dis-

tribution network. A high-speed, bi-direction, real-time andintegrated communication system is needed. The construction

of communication system needs to focus on the following:

open communication architecture, in order to form a plug and

play environment; unified technique standards, in order to

achieve seamless communication among equipments and sys-

tems.

(3)Unified information platform. The problems of existing

information systems are as follows: lack of unity of data

source, lack of data maintenance in time and lack of coordina-

tion. A unified information platform with the characteristics of

a wide-range of information source, support bi-direction in-

formation flow and data sharing should be developed.


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3.3 Develop intelligent application

At present the data application of network in China is

still in the basic level. Intelligent application should be en-

hanced in order to meet the requirements of smart distribu-

tion network.

(1)Fast simulation and modeling. The achievement of fastsimulation and modeling is to offer decision-making support

for relay protection, network reconfiguration, fault isolation

and restoration by means of state estimation, power flow cal-

culation, load forecasting, security evaluation and predictive

contingency analysis.

(2)Operation optimization. To minimize the line loss under

normal condition, optimize operation mode under overhaul

condition and realize fast restoration under fault condition in

order to keep the distribution network operate in security and

economy.

(3)Intelligent dispatch. With the development of advanced

sensing technology, wide-area measurement system (WAMS)and advanced metering infrastructure (AMI), observability of

network is strengthened. Its probable to achieve real-time

state estimation and precise control of the whole network.

Dispatch in smart distribution network is more complicate and

difficult due to the grid-connection of distributed energy and

the bi-direction flow of energy.

(4)Intelligent control. Deep interaction between consumers

and power system make intelligent control a multi-objective

problem. Besides security, reliability and economy, which are

considered in traditional network, energy conservation and

emission reduction as well as improvement of efficiency

should be taken account of.(5)Grid-connection of distributed energy resource. After the

distributed energy resource connected to the traditional distri-

bution network, the configuration of relay protection and

safety automatic devices become more complicate and should

be reset to satisfy the bi-direction flow of load and information.

The power output of distributed energy changes now and

again, with the characteristics of fluctuation and intermittence,

and is prone to bring shock to power system.

Besides network infrastructure, intelligent distribution

equipments, communication technology and information

technology as mentioned above, standard systems are also

indispensable[15]. Based on the unified standard, information

interaction, communication and resource sharing among

equipments and systems become more convenient.

4 Development path of smart distribution net-

work

The development path of smart distribution network in

China should be based on the development status and com-

bined with the development concept in China as well as

oversea experience.

(1)Strengthen the construction and optimization planning of

distribution network to form a strong and flexible physical

entity network of sufficient power supply capability and high

reliability.

(2)Upgrade distribution automation and self-healing control

in order to keep power system operate in security, reliability,

economy and efficiency.

(3)Construction of information and communication system.Besides electric power technology, smart distribution network

needs information and communication system with the cha-

racteristics of high-capacity, high-speed, real-time and ex-

tensibility as supporting platform.

(4)Strengthen the interaction with consumers. It is neces-

sary to develop further research on grid-connection of distri-

buted energy, energy storage technology and charging man-

agement of electric vehicle in order to provide solution for

consumers.

(5)Development of exploratory research. Smart grid means

important technological innovation; we should make every

effort to exploratory research.Smart distribution network is a systemic project and needs

a wide range of support: policy support and financial support

of the government in order to provide a good external envi-

ronment, combination research of research institutes, power

industry and equipment manufacturer.

5 Conclusion

The construction of smart distribution network in China will

be a long and arduous process. Further research on network

infrastructure, information and communication system, in-

telligent application and unified standard system are neces-

sary.

Smart distribution network needs support of government

and cooperation of research institute, power industry and

equipment manufacturer.

Along with the development and the further research of the

smart distribution network, the technical framework and its

development path will become more clear.

This work was supported by the Science and Technology Projects of StateGrid Corporation of China (Grant No. ND71-10-005, No. ND71-11-002).

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